Because the article relies heavily on numbers, much of it divined through the work of the Augmented Social Cognition group at Parc in California, I thought it was worth running through some of them here and highlighting some of the most interesting statistics.

First, I have to say, there are some really good numbers from stats.wikimedia.org, who do an amazing job of providing information despite the vast size of the database they're dealing with. From this graph you can see a little of the growth pattern: what was exponential growth between 2003 and 2007 has turned into steady growth since then. The curve doesn't change drastically, but that's sort of the point - it's steady, not hockey stick growth.

Parc's ASC team has a great blog worth reading for more, but two areas of the study are pretty illuminating. Editing activity is biased towards power users - those who contribute more than 100 edits each month.

Meanwhile, the number of reverts - when somebody effectively clicks the undo button - has gone up massively, while remaining static for those power users.

Note: this data excludes activity by vandals or bots.

I find this fascinating. Does this show that Wikipedia is organising itself differently? And how? Has the community reached its natural limit?

One final thing: I was also intrigued by the comment by Ed H Chi that ends the article - that the closest model for this is "population growth studies... where there's some sort of resource constraint".

What, precisely, is the resource that is constrained on Wikipedia? Is it the number of editors (and by extension) the amount of time they have to edit? I am sceptical of this argument, since nobody is theoretically barred from contributing and there are more than a billion people online. Is it that enough human knowledge has been collected - the easy blanks filled in - that there is less new material to contribute? I certainly hope humanity can't be distilled into three million articles of encyclopedic knowledge.

So what exactly is the scarce resource that's changing the face of Wikipedia? Any ideas?

(Updated to fix missing third image of edits excluding robots and vandals.)

Thanks to the ASC group at Parc for their work, especially those graphs we've reproduced. The full details of the will be published to time with the WikiSym 2009 event in Orlando this October, but in the meantime, the team has been posting some data on their blog.